Sheet feeding device and image forming device

ABSTRACT

A sheet feeding device includes: a sheet stacker that stores a sheet in a stacked state; a separating air blower that blows air to a sheet from a leading end side in a sheet feeding direction of the stacked sheet; a floating air blower that blows air to a sheet from both sides of a sheet end orthogonal to the sheet feeding direction of the stacked sheet; an attractor that attracts an uppermost sheet that has been floated; a blow direction switcher that changes a blow direction of the floating air blower to an arbitrary direction; and a hardware processor that controls change in the blow direction of the floating air blower by the blow direction switcher in accordance with at least one of a basis weight, a size, and a floating property of a sheet.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese patent Application No. 2017-092728, filed on May 9, 2017, the entire content of which is incorporated herein by reference.

BACKGROUND Technological Field

The present invention relates to a sheet feeding device and an image forming device.

Description of the Related art

In the related art, there is a known sheet feeding device of an air suction type in an image forming device that forms an image on a sheet, in which sheets are stored in a stacked state and a sheet is supplied to an image former.

Such a sheet feeding device of the air suction type includes: a floating air blower that floats upper sheets by blowing air to sheets stacked in a sheet stacker from both sides in a direction orthogonal to a sheet conveyance direction; a separating air blower that separates an uppermost sheet from other sheets by blowing the air from a leading end side in the sheet conveyance direction of the uppermost sheet; and a belt conveyance mechanism that conveys a sheet in the conveyance direction by using a conveyance belt located above the stacked sheet while attracting the sheet. Since only the uppermost sheet is attracted and separated from other sheets by the above-described mechanisms, the sheets can be sent one by one onto a sheet conveyance path.

However, in a case where a sheet is heavy or large, floating force applied by the floating air and separating air is not sufficient, and there may be a case where a sheet cannot be conveyed.

To solve such a problem, JP 2014-169182 A discloses a technology in which floating force is enhanced by blowing floating air and separating air in directions in which these two kinds of air collide with each other. During this time, a floating state of a sheet may become unstable due to collision between the two kinds of air, and therefore, a mechanism to suck air from a rear end side of a sheet is provided.

In a condition that a sheet is hardly floated, it is necessary to blow strong floating air, and in a case of using the invention disclosed in JP 2014-169182 A, collision of two kinds of air is further increased, and it is necessary to suck air from a rear end side with strong suction force due to the increase of collisions.

However, in a case where the suction force becomes strong, a sheet may be unexpectedly sucked, and therefore, it is difficult to stabilize an air flow while keeping strength of the air.

SUMMARY

The present invention has been made in view of the above-described problems, and an object thereof is to provide a sheet feeding device and an image forming device in which sheet feeding is stably performed even in a condition that a sheet is hardly floated.

To achieve the abovementioned object, according to an aspect of the present invention, a sheet feeding device reflecting one aspect of the present invention comprises:

-   -   a sheet stacker that stores a sheet in a stacked state;     -   a separating air blower that blows air to a sheet from a leading         end side in a sheet feeding direction of the stacked sheet;     -   a floating air blower that blows air to a sheet from both sides         of a sheet end orthogonal to the sheet feeding direction of the         stacked sheet;     -   an attractor that attracts an uppermost sheet that has been         floated;     -   a blow direction switcher that changes a blow direction of the         floating air blower to an arbitrary direction within a range         from a direction in which the floating air is blown to a leading         end side in the sheet feeding direction of the stacked sheet to         a direction in which the floating air is blown to a rear end         side; and     -   a hardware processor that controls change in the blow direction         of the floating air blower by the blow direction switcher in         accordance with at least one of a basis weight, a size, and a         floating property of a sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention:

FIG. 1 is a diagram illustrating a schematic structure of an image forming device;

FIG. 2 is a block diagram illustrating main functional components of the image forming device;

FIG. 3A and FIG. 3B are perspective views of a sheet feeder of the image forming device;

FIG. 4 is a partial side view illustrating a sender, an attractor, and a conveyor in the sheet feeder;

FIG. 5A to FIG. 5C are plan views illustrating operation of a blow direction switcher of the sheet feeder;

FIG. 6 is a plan view illustrating the sender, attractor, and conveyor of the sheet feeder;

FIG. 7A to FIG. 7D are side views illustrating states of a sheet in sheet feeding operation of the sheet feeder;

FIG. 8A to FIG. 8C are plan views to describe a blow direction of floating air; and

FIG. 9 is a flowchart illustrating operation of the image forming device.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. Note that various technically-preferable limitations in order to implement the embodiment of the present invention are provided, but the scope of the invention is not limited to the disclosed embodiments and illustrated examples.

Structure of Image Forming Device

FIG. 1 is an entire structural view of an image forming device 100 according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating functional components of the image forming device 100.

As illustrated in FIG. 1 and FIG. 2, the image forming device 100 mainly includes an image forming device main body 100 a, an image reading device SC, an automatic document feeding device DF, an image processor 30, a sheet feeding device 500, a controller 400, a storage 410, and a communication unit 420.

The image forming device main body 100 a includes: an image former 10 including a photoreceptor 1, a charging unit 2, an image exposing unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and the like; a fixing unit 7; and a sheet conveyance system. The sheet conveyance system includes a first sheet feeder 11, a second sheet feeder 12, a sheet feeding cassette 13, a sheet ejector 14, a conveyance path switcher 15, a circulating re-feeder 16, and a reversed sheet ejector 17.

The sheet feeding device 500 includes three sheet feeders 50 arranged in the vertical direction.

(1) Image Processor

The image processor 30 applies various kinds of image processing to image data, and transmits an image signal to the image former 10.

An image of one side or images of both sides of a sheet d placed on a document platen of the automatic document feeding device DF is read by an optical system of the image reading device SC and then read by an image sensor CCD. The image processor 30 applies analog processing, AID conversion, shading correction, image compression processing, and the like to an analog signal photoelectrically converted by the image sensor CCD, and then transmits an image signal to the image exposing unit 3.

Additionally, the controller 400 can communicate with an external device (such as a personal computer) connected to a communication network from the communication unit 420, and the image processor 30 sometimes transmits, to the image exposing unit 3, an image signal received from the external device under control of the controller 400.

(2) Image Former

In the image former 10, the photoreceptor 1 is electrically charged by the charging unit 2, an electrostatic latent image is formed by laser light emitted from the image exposing unit 3, and the electrostatic latent image is developed as a toner image by the developing unit 4. Subsequently, a sheet P stored in the sheet feeding cassette 13 is conveyed from the first sheet feeder 11. The sheet P is conveyed by the second sheet feeder 12 including a registration roller in synchronization with a toner image. After that, the toner image is transferred to the sheet P by the transfer unit 5 and then fixed by the fixing unit 7. Meanwhile, a toner remaining on the photoreceptor 1 from transfer operation is removed by the cleaning unit 6.

Additionally, instead of a sheet P stored in the sheet feeding cassette 13, a sheet P stored in the sheet feeding device 500 is also fed to the image forming device main body 100 a, and a toner image is transferred and fixed onto this sheet P.

A sheet P subjected to fixing is ejected to the outside of the device by the sheet ejector 14. Meanwhile, in a case of double-sided printing, a sheet P having a first face formed with an image is fed to the circulating re-feeder 16 by the conveyance path switcher 15, and the sheet is reversed and then ejected to the outside of the device by the sheet ejector 14 after an image is formed again on a second face in the image former 10. In a case of reversed sheet ejection, a sheet P that has been conveyed through a path branched from a normal sheet ejection path is switched back and turned upside down in the reversal sheet ejector 17, and then ejected to the outside of the device by the sheet ejector 14.

(3) Sheet Feeding Device

FIG. 3A is a perspective view illustrating an overview of the sheet feeder 50 of the sheet feeding device 500. As described above, the three sheet feeders 50 are provided in the sheet feeding device 500 in a manner arrayed in vertical direction, but here, a description will be provided for one sheet feeder 50 here because all of the sheet feeders have the same structure.

A sheet feeder 50 includes: a sheet stacking table 511 serving as a sheet stacker that places a plurality of sheets P in a stacked state and is horizontally set; a rear end regulating member 512 provided on a rear side of the sheet stacking table 511, namely, an upstream side in a sheet feeding direction a; and a leading end regulating member 513 provided on a front side of the sheet stacking table 511, namely, a downstream side in the sheet feeding direction a.

Meanwhile, in the following description of the sheet feeder 50, a direction that is horizontal and orthogonal to the sheet feeding direction a and is located a left hand side in the view of the sheet feeding direction a will be defined as a “left” side and a direction that is horizontal and orthogonal to the sheet feeding direction a and is located on a right side in the view of the sheet feeding direction a will be defined as a “right” side.

The sheet stacking table 511 is supported in a manner movable inside the sheet feeder 50 in a vertical direction, and the rear end regulating member 512 and the leading end regulating member 513 are installed in a manner fixed inside the sheet feeder 50.

A height of an upper end of the leading end regulating member 513 is lower than that of an upper end of the rear end regulating member 512. On the other hand, the sheet stacking table 511 is vertically moved by an actuator not illustrated, and the actuator is controlled by the controller 400 such that an uppermost portion of sheets P stacked on the sheet stacking table 511 is kept at a prescribed height slightly lower than the upper end of the leading end regulating member 513. Meanwhile, such height control by the actuator is performed on the basis of a sensing result by a sensor (not illustrated) that is provided on the rear end regulating member 512 side and detects the height of the uppermost sheet P.

Furthermore, the sheet stacking table 511 can be moved downward when there is no sheet to be fed, for example, when sheets P are resupplied.

A separating air blower 52 disposed adjacent to the leading end regulating member 513 is provided on the downstream side in the sheet feeding direction a of the leading end regulating member 513. Additionally, floating air blowers 53 and 54 are provided on both of left and right sides of the sheet stacking table 511 respectively, and an inner side surface of each of the floating air blowers 53 and 54 is flat and formed in a vertical direction and functions as a regulating member that regulates a sheet position in a lateral direction.

Meanwhile, the floating air blowers 53 and 54 are provided in a manner movable in the lateral direction by an actuator not illustrated, and the actuator is controlled by the controller 400 such that wall surfaces of the floating air blowers 53 and 54 are located at positions contacting ends in a width direction of a sheet. Additionally, the position in the lateral direction of the sheet regulated by the actuator is determined on the basis of size information of the sheets stacked in the sheet feeder 50 stored in the storage 410.

A blowing fan 521 and blowing fans 531 and 541 are provided inside the separating air blowers 52 and the floating air blowers 53 and 54 respectively, and air is blown from blow ports 522, 532, and 542, respectively.

FIG. 3B is a view of a main portion structure of the floating air blower 54. Note that a view of a main portion structure of the floating air blower 53 will be omitted because the floating air blower 53 have the structure similar to the floating air blower 54.

As illustrated in FIG. 3B, the floating air blowers 53 and 54 include nozzle 533 and 543 respectively in order to blow air toward an uppermost sheet P in a horizontal direction or in a direction inclined slightly higher than the horizontal direction from the right and left sides of the uppermost sheet P positioned at a regulated height. The blow ports 532 and 542 of the respective nozzles 533 and 543 are formed such that upper edges of the nozzles are located lower than the uppermost sheet P positioned at the regulated height.

As illustrated in FIG. 3A and FIG. 3B, the floating air blowers 53 and 54 include blow direction switchers 534 and 544, shafts 535 and 545, pairs of gears 536 and 546, and motors 537 and 547, respectively.

The blow direction switchers 534 and 544 are arranged between the stacked sheets and each of the blow ports 532 and 542 respectively, and provided in manner rotatable around the shafts 535 and 545 respectively. Drive force by the motors 537 and 547 is transmitted to the shafts 535 and 545 by the pairs of gears 536 and 546 to rotate the shafts 535 and 545. Note that the blow direction switchers 534 and 544 are formed such that upper edges thereof are located higher than the uppermost sheet P positioned at the regulated height.

In other words, upper sheets P can be floated upward by blowing air from the respective blow ports 532 and 542 and then introducing floating air by the blow direction switchers 534 and 544 in a manner blowing the air in an upward oblique direction with respect to a surface of the upper sheets P in a stacked state.

FIG. 4 is a cross-sectional view illustrating a structure in the periphery of the leading end in the sheet feeding direction a of an uppermost sheet P in the sheet stacking table 511.

The separating air blower 52 includes a nozzle 523 in order to blow air from the blow port 522 in the direction inclined slightly higher than a direction on the downstream side in the sheet feeding direction a, and sheets other than the uppermost sheet P can be separated and moved downward by blowing air to leading ends on the downstream side in the sheet feeding direction a of a plurality of sheets that have been floated by the floating air blowers 53 and 54, and then blowing the air to between the floated sheet P and other sheets.

FIG. 5A to FIG. 5C illustrate a relation between an orientation and a blow direction of the blow direction switcher 544.

In the following, a direction orthogonal to the sheet feeding direction a is defined as a lateral direction b, and a side surface out of side surfaces of the blow direction switcher 544 connected to the shaft 545 is defined as a rotational face 544 a.

For example, as illustrated in FIG. 5A, when the rotational face 544 a is stopped at an angle 90 degrees (θ1) with respect to the lateral direction b, the floating air is blown from the blow port 542 in a direction orthogonal to the sheet feeding direction a.

On the other hand, as illustrated in FIG. 5B, when the rotational face 544 a is stopped at an angle (θ2) at which the rotational face 544 a faces a rear end side of a sheet in the lateral direction b, the floating air is blown to the upstream side in the sheet feeding direction a (rear end side of the sheet).

Furthermore, as illustrated in FIG. 5C, when the rotational face 544 a is stopped at the angle (θ3) at which the rotation surface faces a leading end side of a sheet in the lateral direction b, the floating air is blown to the downstream side in the sheet feeding direction a (leading end side of the sheet).

In other words, the motors 537 and 547 are driven to rotate the blow direction switchers 534 and 544 under the control of the controller 400, thereby changing the blow direction of the floating air.

FIG. 6 is a plan view of the sender 55 and the attractor 56. As illustrated in FIG. 3A, FIG. 3B, FIG. 4, and FIG. 6, the sender 55 is provided above the sheet stacking table 511. Meanwhile, in FIG. 3A and FIG. 3B, the sender 55 is illustrated in a manner shifted to a position indicated by an arrow so as not to hide a surrounding structure, but actually the sender is arranged above a downstream end in the sheet feeding direction a of the sheet stacking table 511 as illustrated in FIG. 4.

The sender 55 includes: four sets of belts 556 arranged on a sheet feeding surface in the lateral direction orthogonal to the sheet feeding direction a; a motor 551 serving as a sheet feeding drive source to drive these belts 556; and a transmission gear train 552 interposed between the respective belts 556 and the motor 551.

Each of the belts 556 includes: a large diameter roller 553 provided on the upstream side in the sheet feeding direction a; two small diameter rollers 554 and 555 provided on the downstream side in the sheet feeding direction a; and the belt 556 stretched via these rollers 553, 554, and 555. Additionally, torque is applied to the large diameter roller 553 of each belt mechanism from the motor 551 in a direction in which a lower portion of each of the belts 556 is moved in the sheet feeding direction a. Note that a sprocket may also be used instead of the respective rollers 553, 554, and 555.

Additionally, each of the belt 556 has a plurality of small holes penetrating the belt from a front side to a rear side in an entire surface thereof, and a sheet P can be attracted to the lower portion of each of the belts 556 via the respective holes by sucking operation of the attractor 56 described later.

A sheet attraction detector 557 that detects attraction of a sheet to each belt 556 is provided on the upstream side in the sheet feeding direction a of the belt 556. The sheet attraction detector 557 includes: a substantially rod-shaped detection body 557 a supported in a swingable manner; and a photosensitive sensor 557 b.

The detection body 557 a has one end protruding lower than the lower portion of the belt 556, and when a sheet P is attracted to the belt 556, the detection body 557 a is swung and the one end thereof is pushed back upward. Then, the other end of the detection body 557 a is lowered when one end is pushed back upward so as to be located at a position to shield the sensor 557 b. The sensor 557 b informs the controller 400 of change in a light receiving amount caused by shielding the sensor, and makes the controller 400 recognize attraction of the sheet P.

As illustrated in FIG. 3A, FIG. 3B, 4, and 6, the attractor 56 includes: a duct 561 arranged in a state having one end inserted into each of the belts 556 of the sender 55; and a fan 562 located at the other end of the duct 561 and making a pressure inside the duct 561 negative.

The above-mentioned duct 561 has one end side inserted into each of the belts 556 and formed in a substantially rectangular parallelepiped shape, and an opening 561 a is formed in a lower portion thereof. Additionally, external air can be sucked from this opening 561 a by making the pressure inside the duct 561 negative by the fan 562.

The duct 561 is arranged in a manner such that the opening 561 a extends over the lower portions of the four belts 556, and a range corresponding to the opening 561 a in the respective belts 556 serves an attraction region B for a sheet.

With the above-described structure, when upper sheets P on the sheet stacking table 511 is floated by the air blown by the above-described floating air blowers 53 and 54, the sender 55 and the attractor 56 can attract, toward the lower portion of each of the belts 556, an uppermost sheet P floated by suction force generated in the attraction region B, and the sheet P can be sent in the sheet feeding direction a by rotational drive of the respective belts 556.

As illustrated in FIG. 4, a conveyor 57 is provided close to the sender 55 on the downstream side in the sheet feeding direction a. The conveyor 57 includes: an insertion guide 571 that can insert a sheet P sent from the lower portion of the belts 556; large and small conveyance rollers 572 and 573 provided in the middle of the insertion guide 571 and adapted to nip and convey the sheet P to the downstream side in the sheet feeding direction a; a motor (not illustrated) serving as a drive source to drive and rotate the conveyance rollers 572 and 573; and a sheet detector 574 that is a contact type or optical type sensor to detect arrival of a leading end of a sheet P at the insertion guide 571 and passage of a rear end of the sheet P.

The insertion guide 571 is formed in a shape in which an upstream end in the sheet feeding direction a is wide opened and a vertical width of the insertion guide is gradually reduced in the sheet feeding direction a, and the insertion guide has the upstream end in the sheet feeding direction a linked to the conveyance path of a sheet P advancing toward the image forming device main body 100 a.

The large diameter conveyance roller 572 and the small diameter conveyance roller 573 are arranged in a manner contacting each other, and are provided in the insertion guide 571 such that a sheet P passing through the insertion guide 571 passes between the large diameter conveyance roller 572 and the small diameter conveyance roller 573.

The large diameter conveyance roller 572 has a motor (not illustrated) serving as a drive source, and drive of this motor is controlled by the controller 400. Since the small diameter conveyance roller 573 contacts the large diameter conveyance roller 572, reverse rotation torque is transmitted to the large diameter conveyance roller 572 so as to perform co-rotation.

The sheet detector 574 is arranged close to the conveyance rollers 572 and 573 on the upstream side in the sheet feeding direction a, detects presence of a sheet P at a position of the sheet detector 574, and informs the controller 400 of a detection result thereof as needed. In other words, in a case where a detection state is changed from absence of a sheet P to presence thereof, the controller 400 recognizes that a leading end of the sheet P has arrived at the position of the sheet detector 574, and in a case where the detection state is changed from absence of the sheet P to presence thereof, the controller 400 recognizes that a rear end of the sheet P has passed through the position of the sheet detector 574.

Note that that the leading end of the sheet P represents a downstream end in the sheet feeding direction a of the sheet P and the rear end of the sheet P represents an upstream end of the sheet P in the sheet feeding direction a.

(4) Controller

The controller 400 includes a central processing unit (CPU) 401, a read only memory (ROM) 402, a random access memory (RAM) 403, and the like. The CPU 401 reads, from the ROM 402, a program corresponding to processing content, develops the program in the RAM 403, and performs centralized control for operation in the respective blocks of the image forming device 100 (image reading device SC, automatic document feeding device DF, image processor 30, image forming device main body 100 a, sheet feeding device 500, and the like) in cooperation with the developed program. At this point, various kinds of data stored in the storage 410 are referred to. The storage 410 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

Additionally, the controller 400 includes the communication unit 420 including a communication control card such as a LAN card not illustrated, and can perform data exchange with an external device (such as a personal computer) connected to a communication network like a local area network (LAN) and wide area network (WAN).

Method of Controlling Sheet Feeding

A description will be provided for a method of controlling, by the controller 400, sheet feeding operation performed by each of the sheet feeders 50 of the sheet feeding device 500.

In the sheet feeding operation in each of the sheet feeders 50, upper sheets P are floated by floating air blown by the floating air blowers 53 and 54, attracted to the lower portion of each of the belts 556, and sent to the conveyor 57 side. The floated sheets P are attracted to the lower portion of each belt 556, but as illustrated in FIG. 7A, not only an uppermost sheet P but also one or a plurality of sheets below the uppermost sheet is floated. Furthermore, as illustrated in FIG. 7B, other sheets are pushed up by the floating air and closely contact a lower side of the uppermost sheet P.

Therefore, the sheet P attracted to the lower portion of each of the belts 556 and other sheets are separated by blowing separating air to the floated sheets with the separating air blower 52 as illustrated in FIG. 7C, and the sheets other than the sheet P are made to fall down by the own weight.

Here, in a case where a blow amount is not sufficient at the time of starting blowing the floating air, the uppermost sheet P is hardly floated to the lower portion of each of the belts 556, and cannot be attracted to the belts 556 as illustrated in FIG. 7D. A heavy sheet such as a thick sheet (for example, a sheet having a basis weight of 300 g or more) is hardly floated and also a state like FIG. 7D tends to occur. Therefore, in a case of floating this type of sheet, the blow amount of the floating air needs to be increased more than at the time of feeding other types of sheets.

However, in a case where the floating air is too strong after the sheet is floated, a sheet state may become unstable, causing flapping, for example.

Additionally, separation efficiency by the separating air is degraded by continuously blowing the floating air at the time of sheet separation. Particularly, in a case of feeding a soft sheet having low density, like a bulky sheet, a floated sheet is hardly separated. Therefore, an uppermost sheet P and one or a plurality of sheets below the uppermost sheet P are sent to the conveyor 57 side in an adhering state, and multi feed may be caused.

Therefore, after the sheet is floated, the floating air blow amount needs to be reduced relative to a separating air blow amount blown to a leading end of a sheet.

Therefore, in the present embodiment, an air blow amount is controlled by controlling a blow directions of the floating air by the floating air blowers 53 and 54.

First, since a large blow amount is needed to float a sheet P when sheet feeding is started, the separating air and floating air are made to collide with each other by turning the blow directions of the floating air of the floating air blowers 53 and 54 in a leading end direction of the sheet P (toward downstream side in the sheet feeding direction a) respectively as illustrated in FIG. 8A. Since the air having collided with each other is moved upward, strong floating force is generated to float the sheet P.

At this point, the blow direction switchers 534 and 544 are controlled to be turned in a direction in which the blow ports 532 and 542 are opened to the separating air blower 52 side as illustrated in FIG. 8A.

Next, when attraction of the sheet P is detected by the sheet attraction detector 557, the controller 400 determines that the uppermost sheet P is floated. After the sheet P is floated, in a case where the air having colliding with each other is continuously blown to the sheet, the sheet state may become unstable, causing flapping, for example. Additionally, the floating air blow needs to be attenuated in order to separate the uppermost sheet P from sheets underneath. Therefore, after the sheet P is floated, the blow ports 532 and 542 are rotated to a rear end side of the sheet P from the direction in which the blow ports 532 and 542 are opened to the separating air blower 52 side as illustrated in FIG. 8B, and the blow directions of the floating air by the floating air blowers 53 and 54 are swung respectively in the rear end direction of the sheet P (toward upstream side in the sheet feeding direction a), thereby suppressing excessive floating force and stabilizing an air flow.

Additionally, since a floating or separating property is varied by a sheet type as described above, it is also possible to control the blow direction of the floating air in accordance with the sheet type.

For example, in a case of a light sheet such as a bulky sheet or a thin sheet, it is necessary to reduce the blow amount of the floating air relative to the separating air in order to ensure a separation property. In this case, as illustrated in FIG. 8C, the blow directions of the floating air by the floating air blowers 53 and 54 are respectively turned in the rear end direction of the sheet P (toward upstream side in the sheet feeding direction a) from the start of sheet feeding. In the case of a light sheet, the sheet is sufficiently floated with weak floating air, and therefore, there is no problem even the blow direction of the floating air is turned in the above-described direction from the start of sheet feeding. At this point, the blow direction switchers 534 and 544 controlled to be directed as illustrated in FIG. 8C by rotating the same.

Subsequently, operation of the image forming device 100 will be described with reference to a flowchart in FIG. 9.

First, when a print command is received, the controller 400 acquires sheet information on a sheet specified by a user (step S901). The sheet information includes information on a basis weight and a size of the sheet.

Next, the controller 400 determines, on the basis of the sheet information, whether the sheet is easily floated (step S902). In a case of determining that the sheet is easily floated (step S902: Yes), processing proceeds to step S911, and in a case of determining that the sheet is not easily floated (step S902: No), the processing proceeds to step S903. Here, in a case of a sheet having a basis weight of less than 300 g, it is determined that the sheet is easily floated.

In step S903, the controller 400 controls the motors 537 and 547 to rotate the blow direction switchers 534 and 544 to positions where the floating air is blown in the leading end direction of the sheet. In other words, the blow direction switchers 534 and 544 are arranged in the directions as illustrated in FIG. 8A.

Subsequently, the controller 400 controls the separating air blower 52 and the floating air blowers 53 and 54 to start blowing the separating air and the floating air (step S904), and the sheet attraction detector 557 detects whether the sheet is floated (step S905). In a case where the controller 400 determines that a floated state of the sheet is not detected (step S905: No), the processing proceeds to step S906, and in a case of determining that the floated state of the sheet is detected (step S905: Yes), the processing proceeds to step S908.

In step S906, the controller 400 determines whether a predetermined period has elapsed, and in a case of determining that the predetermined period has not elapsed (step S906: No), the processing proceeds to step S905, but in a case of determining that the predetermined period has elapsed (step S906: Yes), the motors 537 and 547 are controlled to rotate the blow direction switchers 534 and 544 such that the blow directions of the floating air are further directed to the leading end side of the sheet (step S907), and then the processing returns to step S905.

In step S908, the controller 400 controls the motors 537 and 547 to rotate the blow direction switchers 534 and 544 to swing the floating air in the rear end direction of the sheet. In other words, the blow direction switchers 534 and 544 are operated as illustrated in FIG. 8B.

Subsequently, the controller 400 determines whether a sheet is a last page (step S909), and in a case of determining that the sheet is the last page (step S909: Yes), control is finished, but in a case of determining that the sheet is not the last page (Step S909: No), the controller 400 controls the motors 537 and 547 to rotate the blow direction switchers 534 and 544 to positions where the floating air is blown in the leading end direction of the sheet (step S910), and then the processing returns to step S905.

In step S911, the controller 400 controls the motors 537 and 547 to rotate the blow direction switchers 534 and 544 to the positions where the floating air is blown in the rear end direction of the sheet. In other words, the blow direction switchers 534 and 544 are arranged in the directions as illustrated in FIG. 8C.

Subsequently, the controller 400 controls the separating air blower 52 and the floating air blowers 53 and 54 to start blowing the separating air and the floating air (step S912), and determines whether a sheet is the last page (Step S913). In the case of determining that the sheet is the last page (step S913: Yes), control is finished while in the case of determining that the sheet is not the last page (step S913: No), the processing in step S913 is repeated.

As described above, the blow amount is adjusted suitable for sheet floating and sheet separation by changing the blow directions of the floating air depending on the sheet type.

As described above, the image forming device 100 according to the present embodiment includes the separating air blower 52, floating air blowers 53 and 54, and sender 55 having the attractor 56. The floating air blower 53 and 54 further include the blow direction switchers 534 and 544 that can switch blow directions thereof, shafts 535 and 545, the pair of gears 536 and 546, and the motors 537 and 547, respectively. The controller 400 changes the blow directions of the floating air blowers 53 and 54 in accordance with a basis weight, a size, and a floating state of a sheet. Therefore, even in a condition that a sheet is hardly floated, for example, in a case where a sheet is heavy or large, sheets can be stably fed by adjusting a collision amount between the floating air and the separating air.

Furthermore, in the image forming device 100 according to the present embodiment, in a case where the sheet attraction detector 557 detects a floated state of an uppermost sheet P, the blow directions of the floating air blowers 53 and 54 are turned to the upstream side in the sheet feeding direction. Therefore, since the floating air is blown to a sheet rear end side after the sheet is floated, a stable air flow can be obtained without the blow amount becoming excessive.

Additionally, in the image forming device 100 according to the present embodiment, in a case where the sheet attraction detector 557 does not detect a floated state of an uppermost sheet P for the predetermined period, the blow directions of the floating air blowers 53 and 54 are turned to the downstream side in the sheet feeding direction. Therefore, the floating air and the separating air are blown so as to collide with each other until a sheet is floated, thereby achieving strong floating force.

Furthermore, in the image forming device 100 according to the present embodiment, the floating air blowers 53 and 54 also function as regulating members and are movable in the lateral direction. Therefore, even when a sheet size is changed, it is possible to move the floating air blowers to the positions where the floating air can be blown from the vicinity of stacked sheets.

Additionally, the image forming device 100 according to the present embodiment includes the blow direction switchers 534 and 544 in order to blow the air in the horizontal direction or in a direction inclined slightly higher than the horizontal direction. Therefore, since the floating air is blown in a sheet floating direction, the sheet can be efficiently floated.

Meanwhile, according to the above-described flowchart, two kinds of control are performed in accordance with the sheet floating properties, but the blow direction may be changed in accordance with a sheet type, for example, per sheet width. Note that correspondence relation between a sheet type and angles of the blow direction switchers 534 and 544 with respect to the lateral direction b may be prepared in advance as a table form and stored in the storage 410, or may be set by a user in accordance with a sheet type.

Furthermore, the blow direction of the floating air can be changed in accordance with a sheet width size.

For example, in a case where a sheet width is large and the floating air blowers 53 and 54 are positioned apart from each other in the lateral direction, the separating air and the floating air hardly collide with each other. In this case, the separating air and the floating air are made to easily collide with each other by turning the blow direction switchers 534 and 544 more to a center side in the sheet width direction.

Note that correspondence relation between a sheet width and angles of the blow direction switchers 534 and 544 with respect to the lateral direction b may be prepared in advance as a table form and stored in the storage 410, or may be set by a user in accordance with a sheet width.

Other Embodiments

The description has been specifically provided on the basis of the above-described embodiment of the present invention, but the above-described embodiment is a preferred example and an embodiment is not limited thereto.

For example, in the above-described embodiment, the case where a sheet feeding device is mounted on an electrophotographic image forming device has been exemplified, but a type of the image forming device is not limited thereto. For example, the sheet feeding device 500 can be applied to an ink jet type or any type of other image forming devices that form an image on a sheet.

Additionally, in the above-described embodiment, a floated state of a sheet is detected by detecting whether the sheet contacts the detection body 557 a, but not limited thereto.

For example, when a sheet is attracted to the attractor 56, a suction pressure is changed because the opening 561 a is closed. A floated state of a sheet can also be detected by detecting this suction pressure.

Additionally, a reflection type sensors may be provided on both of left and right sides or one side of the side faces of the sheet stacking table 511, and a floated state of a sheet may be detected by detecting reflection light from the floated sheet.

Besides, a detailed structure of each of the devices constituting the image forming device and detailed operation of each of the devices can be suitably modified within a range without departing from the gist of the present invention.

Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims. 

What is claimed is:
 1. A sheet feeding device comprising: a sheet stacker that stores a sheet in a stacked state; a separating air blower that blows air to a sheet from a leading end side in a sheet feeding direction of the stacked sheet; a floating air blower that blows air to a sheet from both sides of a sheet end orthogonal to the sheet feeding direction of the stacked sheet; an attractor that attracts an uppermost sheet that has been floated; a blow direction switcher that changes a blow direction of the floating air blower to an arbitrary direction within a range from a direction in which the floating air is blown to a leading end side in the sheet feeding direction of the stacked sheet to a direction in which the floating air is blown to a rear end side; and a hardware processor that controls change in the blow direction of the floating air blower by the blow direction switcher in accordance with at least one of a basis weight, a size, and a floating property of a sheet.
 2. The sheet feeding device according to claim 1, further comprising a flotation detector that detects a floated state of the stacked sheet, wherein in a case where a floated state of the sheet is detected by a flotation detector, the hardware processor changes the blow direction of the floating air blower in a direction to a rear end side in the sheet feeding direction of the stacked sheet.
 3. The sheet feeding device according to claim 1, further comprising a flotation detector that detects a floated state of the stacked sheet, wherein in a case where a floated state of the sheets is not detected by the flotation detector within a predetermined period from start of sheet feeding, the hardware processor changes a blow direction of the floating air blower in a direction to a leading end side in the sheet feeding direction of the stacked sheet.
 4. The sheet feeding device according to claim 1, wherein the floating air blower is movable in a direction parallel to a surface of the stacked sheet and orthogonal to the sheet feeding direction.
 5. The sheet feeding device according to claim 1, wherein the floating air blower blows air obliquely upward with respect to a sheet surface.
 6. An image forming device comprising: the sheet feeding device according to claim 1; and an image former that forms a toner image on a sheet. 